diff --git a/lib/active_interaction/base.rb b/lib/active_interaction/base.rb
index f54959c3..f75f609a 100644
--- a/lib/active_interaction/base.rb
+++ b/lib/active_interaction/base.rb
@@ -200,7 +200,7 @@ def process_inputs(inputs)
       inputs.each do |key, value|
         fail InvalidValueError, key.inspect if self.class.send(:reserved?, key)
 
-        instance_variable_set("@#{key}", value)
+        instance_variable_set("@#{key}", value) if respond_to?(key)
       end
 
       self.class.filters.each do |name, filter|
diff --git a/spec/active_interaction/base_spec.rb b/spec/active_interaction/base_spec.rb
index f1cceb03..832339ca 100644
--- a/spec/active_interaction/base_spec.rb
+++ b/spec/active_interaction/base_spec.rb
@@ -54,7 +54,7 @@ def execute
       end
     end
 
-    context 'with an attribute' do
+    context 'with a reader' do
       let(:described_class) do
         Class.new(TestInteraction) do
           attr_reader :thing